The present invention relates to a fuel injection valve to be mounted on an internal combustion engine, particularly to a technique for atomizing a fuel injected at a start of an operation of the internal combustion engine.
A fuel injection valve to be mounted onto an internal combustion engine controls an amount of the injected fuel and atomizes the fuel to be injected from an injection port into an intake manifold or combustion chamber of the internal combustion engine. Particularly, since a temperature of the engine is low when the operation of the internal combustion engine is started, there is a probability of that the injected fuel adheres to a wall surface of the intake tube or combustion chamber to decrease a combustion efficiency so that an exhausted amount of unburnt component such as Hydro-carbon or the like is increased. Therefore, the pressurized fuel is injected while decreasing the pressure thereof or the heated fuel is injected so that the atomization and vaporization are accelerated to decrease the exhausted amount of Hydro-carbon.
For example, in a fuel injection valve disclosed by JP-A-2002-4973, an inside of a valve shaft is made hollow, and the valve shaft is formed by a base portion slidable in a cylindrical part of a valve body casing and a shaft portion whose diameter is smaller than that of the base portion to form a fuel path between the shaft portion of the smaller diameter and an inner surface of the valve body casing to communicate with a valve seat so that the fuel is supplied into the fuel path from a fuel outlet port formed on a wall of the valve shaft. Particularly, it is proposed that a heater is arranged on an outer surface of the valve body casing over the fuel path to heat the fuel, and a diameter of a part of the valve shaft over which the heater is arranged is increased to narrow the fuel path to increase a thermal conductivity to the fuel.